In a power semiconductor module, a plurality of power semiconductor chips are mounted on, for example, a metal substrate with an insulating layer interposed therebetween. The power semiconductor chip is, for example, an insulated gate bipolar transistor (IGBT), a metal oxide field effect transistor (MOSFET), or a diode.
In a power semiconductor module, if wiring inductance (hereinafter, referred to as inductance) is large, an over voltage called a surge voltage occurs when switching-off operation is performed at a high speed. In consideration of the surge voltage, if a breakdown voltage of the semiconductor chip is designed to be high, there is a problem that on-resistance of the semiconductor chip increases, and conduction loss becomes large. In addition, by lengthening the time of the off operation, the surge voltage can be reduced. However, there is a problem that switching loss becomes large. Therefore, it is desired to reduce the inductance of the power semiconductor module.